What Is Underpinning and How Does It Save Your Foundation?
Foundations are the backbone of any structure, and when they begin to fail, the entire building can be at risk. Foundation underpinning is one of the most effective methods of stabilizing and strengthening foundations that have experienced settlement or damage.
In today’s blog post, we will explain what underpinning is, why it might be necessary, common underpinning methods, and how it can help you save your foundation.
What is Underpinning in Foundation Repair?
Underpinning is a process used in foundation repair to strengthen or stabilize an existing foundation. It involves deepening or extending the foundation to more stable soil or bedrock, providing additional support to prevent further settling.
This foundation repair method is often required when the original foundation can no longer support the structure due to changes in soil conditions, water table shifts, or poor construction.
Reasons Why Underpinning Might Be Necessary
Several factors can contribute to the need for underpinning, including soil instability and changes in the environment. Below are the primary reasons underpinning might be necessary for your foundation:
Unstable Soil Conditions
- Settlement: Ground movement or settling that causes a foundation to sink can lead to foundation settlement issues. When the soil underneath the foundation shifts, the weight of the structure is no longer evenly distributed, potentially causing structural damage.
- Soil Erosion: Changes in the soil, especially due to water runoff or flooding after a natural disaster, can cause soil beneath the foundation to erode, leading to instability.
- Expansive Clay Soils: Expansive soils, such as those found in San Antonio, expand and contract with moisture content. This fluctuation in soil volume can cause uneven settling and require foundation underpinning to stabilize the structure.
Water Table Changes
Fluctuations in the water table can weaken the soil beneath the foundation, leading to foundation settlement. When the soil becomes overly saturated or dries out, it can shift, causing movement in the foundation.
Poor Construction
Sometimes, the original construction methods or materials used for the foundation may not have been adequate to support the load of the structure. This can lead to foundation failure over time, and underpinning may be necessary to reinforce the foundation and ensure stability.
Original Load-Bearing Capacity is Exceeded
Over time, the original foundation may no longer be sufficient to support the weight of the structure, particularly if additional floors or heavier structures have been added. Underpinning increases the load-bearing capacity of the foundation, providing a permanent solution to these issues.
Most Common Foundation Types
Different types of foundations are used based on soil conditions, climate, and building requirements. Each type of foundation has its own challenges when it comes to foundation repair.
Slab-on-Grade Foundations
Slab foundations are the most common type in Central and East Texas homes. These foundations are poured directly on the ground, and they can be particularly vulnerable to soil movement caused by expansive clay or unstable soil. Underpinning methods, such as concrete underpinning or the use of foundation piers, can help stabilize these types of foundations.
Pier and Beam Foundations
Pier and beam foundations are typically found in older homes. These foundations use concrete or steel piers to elevate the structure above the ground. While they provide good protection against moisture, they can also be susceptible to shifting soil conditions, requiring underpinning methods like helical piers or steel push piers to reinforce the foundation.
Crawl Spaces
Homes with crawl space foundations can face challenges related to soil movement and moisture. Uneven ground conditions can lead to foundation settlement, and underpinning may be necessary to provide additional support to prevent shifting or tilting of the foundation walls.
Common Underpinning Methods
Several underpinning methods are used by foundation repair experts depending on the type of foundation, soil conditions, and the severity of the foundation settlement. Here are the most common methods:
Drilled Concrete Piers
Concrete piers are a traditional method of underpinning that involves drilling holes into the ground and filling them with concrete. This process strengthens the foundation by providing additional support and stabilizing the structure.
Steel Push Piers and Helical Piers
- Helical Piers: These screw-like piers are driven into stable soil layers below the foundation. They are often used in challenging soil conditions to provide a solid foundation for the structure.
- Push Piers: Push piers are heavy-duty steel piers that are driven into the ground to a deeper, stable soil layer. These piers can be used to lift the foundation back to its original position and stabilize it.
Polyurethane Repair
Polyurethane repair involves injecting a polyurethane foam under the foundation to lift and level it. This method is best suited for less severe foundation settlement issues and offers a quick and non-invasive solution to minor foundation problems.
Other Underpinning Foundation Repair Methods
In addition to the common underpinning methods, there are several other techniques that may be used for more specialized situations or in different soil conditions:
- Mass Concrete Underpinning or Traditional Underpinning: This method involves excavating beneath the foundation and pouring a concrete beam to support the structure. It is particularly effective for deep foundation repair and can provide long-lasting results.
- Beam and Base: The beam and base method combines the use of a reinforced concrete beam with a stable base to distribute weight more evenly and prevent foundation settlement.
- Mini-Piled Underpinning: This technique involves the use of smaller steel piles that are drilled deep into the ground to support the foundation. It is ideal for lighter structures or when limited space is available for larger piers.
- Jet Grouting: Jet grouting involves injecting high-pressure grout into the soil to improve its stability. It is a method used in areas with weak or unstable soil to enhance the load-bearing capacity of the foundation.
Choosing the Right Underpinning Method for Your Property
Choosing the appropriate underpinning method is crucial to ensuring a stable foundation. Factors such as soil type, the extent of foundation damage, the foundation type, and the depth of the foundation must all be considered.
A foundation inspection by a professional can help you determine the best approach for your property and ensure that the right foundation repair method is used.
Signs of Foundation Issues That Might Need Underpinning
If you notice any of the following signs of foundation problems, it’s time to consult a foundation repair specialist:
- Cracks in Walls and Floors: Large, uneven cracks in walls and floors, particularly around windows and doors.
- Doors and Windows That Stick: Misaligned doors and windows that no longer open or close smoothly.
- Uneven Floors: Floors that slope or have visible dips or bulges.
- Visible Gaps or Separation: Gaps between walls, ceilings, or the foundation.
- Leaning or Tilting Walls: Walls that appear to be leaning or tilting due to shifting ground conditions.
- Outdoor Foundation Issues: Visible cracks or shifting in the exterior foundation walls, driveway, or patio.
Call Above All Foundation Foundation Repair If You See Any Signs of Foundation Issues
By incorporating effective underpinning methods like helical piers, push piers, or concrete piers, most foundation settlement can be addressed, with your structure stabilized and a permanent solution to your foundation issues being ensured.
If you’re noticing any signs of foundation problems, it’s essential to act quickly. Foundation issues can worsen over time, leading to more expensive repairs and potential structural damage.
Contact Above All Foundation Repair today to schedule a foundation inspection and discuss your foundation repair options. Our team of foundation repair experts can help you choose the right underpinning method and ensure your foundation is stable and secure for years to come.
